Page 85 - Vetus

PREVENTING WATER RUNNING BACK TO THE ENGINE

Installation above or below waterline
The cooling water injection point is crucial. If the water injection point is 6” (15 cm) or more above the waterline, the
cooling water can be injected directly into the exhaust system. But when it is less than 6” (15 cm) above or even below the
waterline, the cooling system can siphon water through the intake when the engine is turned off. Water can fill up the
exhaust system and get back into the engine through the exhaust valves. This can be prevented by using a breather hose (1)
in the cooling water system or an air vent (2).
Calculation tool
π
The waterlock capacity can be easily determined by 2 x ( x D² x L ) x 0,25 / 1000.000
the following formula: 4

D = Internal diameter of the hose (mm)
L = Length of hose (mm) Safety Volume 25% Water Conversion
margin in hose to litres

Gooseneck ➀ ➀ ➁ ➁
Gooseneck
Airvent
Exhaust hose

Exhaust hose Waterline
Waterline

Muffler
Waterlock/Muffler NLP
Transom
connector Transom
connector Waterlock/Muffler NLP
Muffler
Exhaust system with the water injection point “C” Exhaust system with the water injection point “C” below
6” (15 cm) or more above the waterline. or less than 6” (15 cm) above the waterline.

How to choose your perfect exhaust system
The combination of engine and waterlock determines the optimum sound attenuation. By using this table you can choose a
waterlock which is suitable for your engine power and exhaust diameter.

Inlet Exhaust
inches (mm) inches (mm) Type LP, MF, NLP, LSS, LSL, NLPHD Type MV Type MGP, MGS, MGL, LSG, HPW
1 3 /16” 30 1 3 /16” 30 13,6 hp / 10 kW - -
1 9 /16” 40 1 9 /16” 40 24,5 hp / 18 kW - -
1 3 /4” 45 1 3 /4” 45 30 hp / 22 kW - -
2 1 /64” 51 2 1 /64” 51 38 hp / 28 kW - -
2 3 /8” 60 2 3 /8” 60 53 hp / 39 kW - 46 hp / 34 kW
3” 76 3” 76 86 hp / 63 kW - 75 hp / 55 kW
3 1 /2” 90 3 1 /2” 90 121 hp / 89 kW 141 hp / 103 kW 105 hp / 77 kW
4” 102 4” 102 155 hp / 114 kW 181 hp / 133 kW 136 hp / 100 kW
4” 102 5” 127 - - 173 hp / 127 kW
5” 127 5” 127 241 hp / 177 kW 281 hp / 206 kW 211 hp / 155 kW
5” 127 6” 152 - - 256 hp / 188 kW
6” 152 6” 152 345 hp / 254 kW 403 hp / 296 kW 302 hp / 222 kW
6” 152 8” 203 - - 420 hp / 308 kW
8” 203 8” 203 - - 539 hp / 396 kW
8” 203 10” 254 - - 691 hp / 508 kW
10” 254 10” 254 - - 844 hp / 620 kW

Note
Values calculated at a back pressure of 0.1 bar. When a higher back pressure is allowed by the
engine manufacturer, VETUS waterlocks can be used for engines with a higher output than
indicated in this table.

Creators of Boat Systems 85